Most of us have heard about the ability of acupuncture to help alleviate pain, as acupuncture has been used in East-Asian medicine for thousands of years, perhaps by activating our body’s own natural painkillers. But how it actually works at the cellular level is largely unknown.

In a recent University of Michigan study, using brain imaging some of these some of these unknowns have come forward. The study is the first to provide evidence that traditional Chinese acupuncture affects the brain’s long-term ability to regulate pain. The results are published in the September issue of the Journal of NeuroImage. In the study, researchers at the U-M Chronic Pain and Fatigue Research Center showed that acupuncture increased the binding availability of mu-opioid receptors (MOR) in regions of the brain that process and dampen pain signals—specifically the cingulated, insula, caudate, thalamus and amygdala. Opioid painkillers, such as morphine, codeine and other medications, are thought to work by binding to these opioid receptors in the brain and spinal cord.

“The increased binding availability of these receptors was associated with reductions in pain,” says Richard E. Harris, Ph.D., a researcher at the U-M Chronic Pain and Fatigue Research Center and also a research assistant professor of anesthesiology at the U-M Medical School. One implication of this research is that patients with chronic pain treated with acupuncture might be more responsive to opioid medications since the receptors seem to have more binding availability, Harris says. These findings could spur a new direction in the field of acupuncture research following recent controversy over large studies showing that sham acupuncture is as effective as real acupuncture in reducing chronic pain.

“Interestingly both acupuncture and sham acupuncture groups had similar reuctions in clinical pain,” Harris says. “But the mechanisms leading to pain relief are distinctly different.”

The study participants included 20 women who had been diagnosed with fibromyalgia, a chronic pain condition, for at least a year, and experienced pain at least 50 percent of the time. During the study they agreed not to take any new medications for their fibromyalgia pain. Patients also had position emission tomography, or PET, scans of the brain during the first treatment and then repeated a month later after the eighth treatment.

Additional authors were Jon-Kar Zubieta, M.D., Ph.D., David J. Scott, Vitaly Napadow, Richard H. Gracely, Ph.D., and Daniel J. Clauw, M.D.. Funding of the project was supplied by the National Institutes of Health and the Department of Army. § Source: University of Michigan Health System.